1. Field the Invention
The present invention relates to a camera that prevents shifting of the frames of the film.
2. Background of Related Art
A first type of conventional camera has a sprocket between the cartridge chamber and the spool chamber. The sprocket engages the film perforations to feed the film. In other words, a film feeding force is transferred to the film from the sprocket. Because the sprocket is enmeshed with the film perforations in the conventional camera, there is little danger of the film suffering a frame shift even when the camera is shaken or when the camera sustains an outside impact. Frame shift occurs when the film moves from a preset halted position toward the direction of film feeding. However, a second type of conventional camera does not include a sprocket because the film is fed by rotating a spool or a cartridge shaft. In the second type of conventional camera, there is a danger that a frame shift could occur when the camera is shaken or sustains an impact.
A camera equipped with a function to prevent frame shifting is disclosed in Japanese Laid-Open Patent Publication Sho 63-180839, the subject matter of which is incorporated herein by reference. This camera includes: a film passage forming member that maintains the film flatness by pressing on the film from the back of the camera, a film passage forming member spring forcing the film passage forming member against a film-receiving plane, a film pressing spring integrally formed with the film passage forming member spring and film pressing unit on the front end of the film pressing spring, which presses the outside of an effective surface of the film toward the film-receiving plane.
Compared to cameras that do not have a film pressing unit, it is more difficult for film frame shift to occur when the camera is shaken or sustains an outside impact in a camera equipped with the film pressing unit. However, the outside of the effective surface of the film is merely pressed by the pressing unit. Therefore, compared to the conventional camera where the film is fed by a sprocket enmeshing with the film perforations, there are cases where a frame shift cannot absolutely be prevented.